[英]how to capture image after face detection in tracking js
I am using tracking js for face detection. 我正在使用跟踪js进行面部检测。 I successfully detected the face but I don't know how to capture image frame.I want to save the detected face as image.
我成功检测到脸部,但我不知道如何捕捉图像帧。我想将检测到的脸部保存为图像。 This is my HTML page:
这是我的HTML页面:
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>tracking.js - face with camera</title>
<script src="../tracking.js-master/build/tracking-min.js" type="text/javascript"></script>
<script src="../tracking.js-master/build/data/face-min.js"></script>
<link rel="stylesheet" type="text/css" href="face.css">
</head>
<body>
<div class="demo-frame">
<video id="video" class="face-video" width="740" height="560" preload autoplay loop muted></video>
<canvas id="canvas" class="face-canvas" width="740" height="560"> </canvas>
</div>
<script src="faceDetection.js" type="text/javascript"></script>
</body>
</html>
And this is my faceDetection.js file: 这是我的faceDetection.js文件:
window.onload = function() {
var video = document.getElementById('video');
var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');
var tracker = new tracking.ObjectTracker('face');
tracker.setInitialScale(6);
tracker.setStepSize(2);
tracker.setEdgesDensity(0.1);
tracking.track('#video', tracker, { camera: true });
tracker.on('track', function(event) {
context.clearRect(0, 0, canvas.width, canvas.height);
event.data.forEach(function(rect) {
context.strokeStyle = '#ff0000';
context.strokeRect(rect.x, rect.y, rect.width, rect.height);
context.font = '11px Helvetica';
context.fillStyle = "#fff";
context.fillText('x: ' + rect.x + 'px', rect.x + rect.width + 5, rect.y + 11);
context.fillText('y: ' + rect.y + 'px', rect.x + rect.width + 5, rect.y + 22);
});
});
};
You could use getUserMedia api and use download
attribute on <a>
element. 您可以使用getUserMedia api并在
<a>
元素上使用download
属性。 It's a bit tricky and it will not be available on all browsers: 它有点棘手,并不适用于所有浏览器:
First draw the video on canvas: 首先在画布上绘制视频:
tracker.on('track', function(event) {
context.clearRect(0, 0, canvas.width, canvas.height);
event.data.forEach(function(rect) {
context.strokeStyle = '#ff0000';
context.strokeRect(rect.x, rect.y, rect.width, rect.height);
context.font = '11px Helvetica';
context.fillStyle = "#fff";
context.fillText('x: ' + rect.x + 'px', rect.x + rect.width + 5, rect.y + 11);
context.fillText('y: ' + rect.y + 'px', rect.x + rect.width + 5, rect.y + 22);
context.drawImage(video, rect.x, rect.y, rect.width, rect.height, rect.x, rect.y, rect.width, rect.height);
});
});
Create a method to trigger the snapshot: 创建一个触发快照的方法:
var snapshot = function() {
if (localMediaStream) {
document.querySelector('a').href = canvas.toDataURL('image/webp');
}
}
video.addEventListener('click', snapshot, false);
Keep a reference to user media: 保留对用户媒体的引用:
navigator.getUserMedia({video: true}, function(stream) {
localMediaStream = stream;
}, function(error){console.error(error)});
See a rough demo with all the code in action here . 见有行动的所有代码粗略的演示在这里 。 Click on the video and a image should be saved (Note: Using latest Chrome; You may need to fine tune coordinates; Be sure to click snapshot after detection was done correctly).
单击视频,应保存图像(注意:使用最新的Chrome;您可能需要微调坐标;确保在检测正确完成后单击快照)。
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